<input type="range" min="-100" max="100" value="0" step="10" name="power" list="powers">
<datalist id="powers">
 <option value="0" />
 <option value="-30" />
 <option value="30" />
 <option value="++50" />  <!-- 无效的值不会产生刻度 -->
</datalist>

<input type="range" name="a" list="a-values">
<datalist id="a-values">
 <option value="10" label="Low">
 <option value="90" label="High">
</datalist>